Companies that rely on broadcast video and/or audio programs for revenue, such as advertisers, television networks and content providers, wish to know the size and demographic composition of the audience(s) that consume their program(s). Audience measurement companies typically address this need by measuring the demographic composition of a set of statistically selected households and the program consumption habits of the member(s) of those households. For example, audience measurement companies may collect viewing data on a selected household by monitoring the content displayed on that household's television(s) and by identifying which household member(s) are watching that content.
Gathering this audience measurement data has become more difficult as local media playback devices (such as video cassette recorders, digital video recorders, and personal video recorders) have made time shifted viewing of broadcast and other programs possible. For example, prior to the advent of these local media playback devices, televisions were used solely to view tuned broadcast programs. As such, an audience measurement company could monitor all of the television viewing by monitoring the channel to which the television was tuned. However, when a local media playback device is employed, the tuned channel of the television may not be indicative of the program being viewed by the audience. For instance, a television tuned to a particular channel (e.g., 3 or 4) may not be displaying a program it has tuned, but may instead be displaying a program tuned by the local media playback device on a completely difference channel, a recorded program played from a tape, a digital versatile disk (DVD) or hard disk drive, or a program played from another source. Thus, the presence of a local media playback device complicates the audience monitoring process.
A number of different techniques have been proposed for performing audience measurement in the presence of these local media playback devices. Some of these methods seek to detect the presence of blue screen signals which are internally generated by the local media playback devices in an effort to determine the source of the programming displayed on a television at a given time. As used herein, a blue screen signal is any signal generated by a local media playback device which, when supplied to a television, causes the television to display a blue background. A blue screen signal may or may not include information that causes a graphic foreground to be displayed against the blue background.
Local media playback devices generate blue screen signals in a variety of instances. For example, blue screen signals may be displayed: (a) when the local media playback device is displaying a menu to the user or otherwise receiving inputs from a user, (b) during the period before and/or after the local media playback device supplies recorded video signals to a television, (c) when the device is initially powered on and the user has not yet selected a mode of operation, and (d) when a selected source is not providing an input video signal.
An example local media playback device, (in this instance, a vide cassette recorder (VCR)), is shown in FIG. 1. In the illustrated example, the VCR has two input ports, namely, an antenna in port 2 and an audio/video (a/v) line in port 4. The antenna in port 2 is intended to be coupled to an external antenna and/or to an external tuner such as a television. The a/v line in port 4 is intended to be coupled to other sources such as a camcorder, another VCR, a DVD player, a digital video recorder (DVR), a video game, or a personal video recorder (PVR). The illustrated VCR also has two output ports, namely, a radio frequency (RF) output port 6 and an audio/video (a/v) line out port 8, both of which are intended to be coupled to an external display device such as a television or to another type of device (e.g., to another VCR). The RF output port 6 is coupled to an RF modulator 10 which functions in the conventional manner to modulate input signals to produce RF output signals at a predetermined frequency (e.g., at channel 3 or 4).
To enable the VCR to tune to broadcast programs, the illustrated VCR is provided with a conventional RF tuner 12. The RF tuner 12 is coupled to the antenna in port 2 to enable attachment of an antenna to the tuner 12.
To enable the playback of recorded media, the VCR of FIG. 1 is also provided with a conventional tape playback mechanism 14. This playback mechanism 14 typically includes a recording mechanism to enable recordation of programs tuned by the tuner 12 or otherwise input via one of the input ports 2, 4.
The VCR of FIG. 1 has a number of output modes. For example, it may simply pass a tuned broadcast program received from an external tuner such as a television tuner via, for example, the antenna in port 2 to the RF modulator 10 via the tuner bypass switch 16. Alternatively, the mode switch 18 may be activated in response to a user command to deliver the signal tuned by the internal tuner 12 of the VCR to the output ports 6, 8. In other operating modes, the mode switch 22 may respond to a user command by coupling the signal generated by the tape playback device 14 or a signal input by the a/v line in port 4 to the output ports 6, 8.
The illustrated VCR is further provided with a blue screen signal generator 20. The blue screen signal generator 20 may output a blank blue screen and/or a blue screen with text or other characters. When appropriate, the VCR control logic (not shown) cause the mode switch 18 to couple the signal generated by the blue screen signal generator 20 to the output ports 6, 8.
Although the presence of a blue screen signal alone does not precisely define the operating mode of the local media playback device, it does indicate that a local media playback device is operational. Therefore, it is desirable to detect the presence of a blue screen signal.